Spectral karyotyping (SKY) is a novel technique based on the simultaneous hybridization of 24 fluorescently labeled chromosome painting probes. It provides a valuable addition to the investigation of many tumors that can be difficult to define by conventional banding techniques. One such tumor is neuroblastoma, which is often characterized by poor chromosome morphology and complex karyotypes. Ten primary neuroblastoma tumor samples initially analyzed by G-banding were analyzed by SKY. In 8/10 tumors, we were able to obtain additional cytogenetic information. This included the identification of complex rearrangements and material of previously unknown origin. Structurally rearranged chromosomes can be identified even in highly condensed metaphase chromosomes. Following the SKY results, the G-banding findings were reevaluated, and the combination of the two techniques resulted in a more accurate karyotype. This combination allows identification not only of material gained and lost, but also of breakpoints and chromosomal associations. The use of SKY is therefore a powerful tool in the genetic characterization of neuroblastoma and can contribute to a better understanding of the molecular events associated with this tumor.
"Image acquisition was performed by use of an SD200 Spectracube (Applied Spectral Imaging) mounted on an Olympus BH-2 microscope using a custom-designed optical filter (SKY-1, Chroma Technology, Brattleboro, VT). Automatic identification of chromosomes was based on the measurement of the spectrum for each chromosome as described previously . At least 20 metaphase cells were analyzed for each of U2OS untreated, scrambled and LAP2β KD clones. "
[Show abstract][Hide abstract] ABSTRACT: Polyploidy has been recognized for many years as an important hallmark of cancer cells. Polyploid cells can arise through cell fusion, endoreplication and abortive cell cycle. The inner nuclear membrane protein LAP2beta plays key roles in nuclear envelope breakdown and reassembly during mitosis, initiation of replication and transcriptional repression. Here we studied the function of LAP2beta in the maintenance of cell ploidy state, a role which has not yet been assigned to this protein.
By knocking down the expression of LAP2beta, using both viral and non-viral RNAi approaches in osteosarcoma derived U2OS cells, we detected enlarged nuclear size, nearly doubling of DNA content and chromosomal duplications, as analyzed by fluorescent in situ hybridization and spectral karyotyping methodologies. Spectral karyotyping analyses revealed that near-hexaploid karyotypes of LAP2beta knocked down cells consisted of not only seven duplicated chromosomal markers, as could be anticipated by genome duplication mechanism, but also of four single chromosomal markers. Furthermore, spectral karyotyping analysis revealed that both of two near-triploid U2OS sub-clones contained the seven markers that were duplicated in LAP2beta knocked down cells, whereas the four single chromosomal markers were detected only in one of them. Gene expression profiling of LAP2beta knocked down cells revealed that up to a third of the genes exhibiting significant changes in their expression are involved in cancer progression.
Our results suggest that nuclear fusion mechanism underlies the polyploidization induction upon LAP2beta reduced expression. Our study implies on a novel role of LAP2beta in the maintenance of cell ploidy status. LAP2beta depleted U2OS cells can serve as a model to investigate polyploidy and aneuploidy formation by nuclear fusion mechanism and its involvement in cancerogenesis.
"All cases were studied using G-banding and SKY according to standard procedures  . Except for case 20, all other cases were previously published: cases 1–10 in , cases 11–17 in  and cases 18–19 in . Case 20 is the cell line STA-BT-1 that was generated from glioblastoma multiform cells of a patient who was born in November 1972 and suffered from neurofibromatosis type 1, non-Hodgkin lymphoma, (chemo-and radiation therapy of the brain), and glioblastoma grade IV, (radio therapy 40 Gy), and who died in April 1990. "
[Show abstract][Hide abstract] ABSTRACT: Malignant solid tumors are commonly characterized by a large number of complex structural and numerical chromosomal alterations, which often reflect the level of genomic instability and can be associated with disease progression. The aim of this study was to evaluate whether chromosomes that harbor primary aberrations have a higher susceptibility to accumulate further alterations. We used spectral karyotyping (SKY), to compare the individual chromosomal instability of two chromosome types: chromosomes that have a primary aberration and chromosomes without an aberration, in 13 primary childhood neural tumors and seven cell lines. We found that chromosomes that contain a primary aberration are significantly (p-value<0.001) more likely to gain further structural rearrangements or to undergo numerical changes (22.6%, 36 of 159 chromosomes) than chromosomes with no initial aberration (4.9%, 54 of 1099 chromosomes). These results are highly suggestive that aberrant chromosomes in solid tumors have a higher susceptibility to accumulate further rearrangements than "normal" chromosomes.
Cancer Letters 05/2007; 250(1):47-52. DOI:10.1016/j.canlet.2006.09.015 · 5.62 Impact Factor
"This diverse biological behavior makes NB a paradigm for the investigation of genomic alterations and associating it with clinical outcome. In neuroblastoma, genomic alterations have been investigated by cytogenetic, and molecular methods including spectral karyotyping and metaphase comparative genomic hybridization (M-CGH)     . Here, we focus on DNA copy number alterations in NB detected by the recently developed cDNA array-based comparative genomic hybridization (A-CGH). "
[Show abstract][Hide abstract] ABSTRACT: Neuroblastoma (NB) is one of the most common pediatric solid tumors and displays a broad variety of genomic alterations. Array-based comparative genomic hybridization (A-CGH) is a novel technology enabling the high-resolution detection of DNA copy number aberrations. In this article, we outline features of this new technology and approaches of data analysis. We focus on stage specific DNA copy number variations in neuroblastoma detected by cDNA array-based comparative genomic hybridization (A-CGH). We also discuss hypothetic evolutionary models of neuroblastoma progression that can be derived from A-CGH data.
Cancer Letters 11/2005; 228(1-2):71-81. DOI:10.1016/j.canlet.2004.12.056 · 5.62 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.